This investigation consists of the application of an integrated sequence of analytical methods for tracing movements of calcium through and around cells closely associated with developing dentin and enamel. Special methods of tissue preparation and sectioning are being used for analysis of the same area of a particular specimen by light microscopic autoradiography, SEM x-ray energy dispersive element analysis and ultrastructural cytochemistry. In addition freeze drying methods are being applied to reduce the loss of diffusible calcium. Developing teeth from frogs and the rat incisor serve as models for the investigations of calcium movement under normal circumstances. In addition, the same analytical procedures are applied to rat incisors in which amelogenesis has been altered in predictable patterns induced by injections of fluoride, strontium or cobalt. Data from the various approaches to be followed will be correlated in an attempt to clarify the currently confused picture of the movements of calcium in its relation to developing enamel and dentin and their formative cells.